Cooling system for an electron tube released on a trajectory

ABSTRACT

A cooling device for electron tubes, exploiting the vaporization of a liquid contained in sealed tanks, surrounding the tube anode. The vaporization of the liquid is controlled by a valve associated with the tanks. The blowoff pressure of this valve is equal to the vaporization pressure at the selected temperature of operation.

United States Patent Inventor Appl. No Filed Patented Assignee PriorityAuguste H. Raye Paris, France July 5, 1968 Feb. 2, 1971 CSF-CompagnieGenerale De Telegraphie Sans Fil a corporation of France July 10, 1967France COOLING SYSTEM FOR AN ELECTRON TUBE RELEASED ON A TRAJECTORY 2Claims, 5 Drawing Figs.

US. Cl 313/18, 313/20, 313/44, 165/32 Int. Cl H0lj 7/28, H0 1 j 61/52[50] FieldofSearch ..313/13,18. 19.20.21. 34.44; 165/1. 13.31,32,37.38

[56 References Cited UNITED STATES PATENTS 3,269,458 8/1966 Rodgersl65/32X 3,404,730 10/1968 Kurisu 165/32 Primary ExaminerRoy LakeAssistant ExaminerE. R. LaRoche Att0rneyCushman, Darby & CushmanABSTRACT: A cooling device for electron tubes, exploiting thevaporization of a liquid contained in sealed tanks, surrounding the tubeanode. The vaporization of the liquid is controlled by a valveassociated with the tanks. The blowoff pressure of this valve is equalto the vaporization pressure at the selected temperature of operation.

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ou m7 I l l l I I l l l l I t 2 6 8p an: Q K .m. \Q a? w L UTEOQ COOLINGSYSTEM FOR AN ELECTRON TUBE RELEASED ON A TRAJECTORY The presentinvention relates to electron tube cooling systems which can operateindependently.

It is well known, where the cooling of the anodes of electron tubes isconcerned, to employ a fluid in contact therewith to dissipate theenergy collected thereby. These fluids. either gaseous or liquid. may beair, water. etc.

The circulation of the fluid may be achieved in a variety of waysdepending upon the nature of the fluid and upon the particularconditions. Thus, the fluid fed in at the input to the cooling system isdischarged to the exterior after passing over the anode, or it isregenerated after passing over the anode. before being reintroduced atthe input.

Other systems having a limited useful life use a fixed quantity of fluidwhich is neither renewed nor regenerated.

For this kind of systems to operate correctly, however, means must beprovided for regulating the rate of consumption of the fluid duringoperation.

According to the invention there is provided a cooling arrangement fordissipating heat generated by a heat producing system comprising: atight enclosure for a predetermined amount of cooling liquid in thermalcontact with said system, said enclosure comprising a valve; and meansfor adjusting the blowoff pressure of said valve as a function of thevaporization pressure of said liquid at a predetermined temperature.

For a better understanding of the invention and to show how the same maybe carried into effect reference will be made to the drawingsaccompanying the following description and in which:

FIG. 1 illustrates an elevational section of one embodiment of theinvention;

FIG. 2 illustrates a plan view of the device of FIG. 1;

FIG. 3 shows a diagram explaining the operation of the device accordingto the invention;

FIG. 4 illustrates the experimental figures obtained with the device ofFIG. 1; and

FIG. 5 illustrates a detail.

FIGS. 1 and 2, in which similar references designate similar elements,illustrate an embodiment of a device according to the invention.

The hot part of the tube is formed, for example, by a ring I,incorporated into the tube, and the cooling system by two sealed tanks 2and 3, provided centrally with respective partitions 8 and 9 and filledwith water.

A circular tight groove 4 is formed either in the wall 5, common to thetwo tanks, or in the ring 1, as in the example illustrated, and providescommunication between the two tanks through the medium of the labyrinthorifices 6 and 7.

The two partitions 8 and 9 and the tank walls are made of a materialhaving good thermal conductivity in order to facilitate heat transfer tothose zones which are bathed by the water. The partitions have holes,which have not been illustrated, to provide communication between thetwo parts of each tank and increase the heat-exchange area.

Each tank has an aperture 10 and 11, which can be closed off by means ofa plug, which plugs have not been illustrated, sealed, for example, bymeans of rubber O-ring seals.

One of the tanks 3 is equipped with a steam blow out pipe 12, whichpasses through the tank wall and is sealed in relation thereto by asolder ring 12'.

Inside the pipe 12, there is a valve 13 with a bias spring 13, thelatter seating against the tube 12 through which, in operation, thevapor is bled off at 12''.

The vapor is bled ofithrough a tube 15 the end 16 of which is locatedabove the water level.

The baffles 6 and 7 are designated for preventing water from flowingfrom one tank into the other during handling of the assembly.

. In gaps between the two tanks the magnets 17 and 18, required for theoperation of the electron tube, are located.

The volume of the tanks is determined as a function of the time ofoperation and power to be dissipated, and a quantity of watercorresponding to about half the total volume of the tanks is introducedthrough one of the orifices I0 or II. With the two tanks open toatmospheric pressure. a check is made to ensure that the levels in thetanks are the same and then the orifices l0 and I I are sealed by tightplugs.

In operation, when the tube heats up. the heat is conducted to the waterby the partitions 8 and 9 and the walls ofthe tanks 2 and 3.

The references I9. 20 and 21 indicate water levels in the tanks 2 and 3.when the tube, having been ejected the face A forward from the missilewhich carried it. undergoes a longitudinal deceleration of O, l, or l0g. and is at the same time imparted a radial acceleration of the orderof l g., the liquid then respectively occupying the volumes situatedapproximately at the left of the line 19, above the line 20, and abovethe line 21.

The hatched portion of the tanks, as shown in FIG. 1, is thus a zone inwhich there is no liquid when the said longitudinal deceleration andradial acceleration conditions are produced, i.e. at the end of someminutes of operation of the device, and at the time when the temperaturereaches a sufficient level for the valve to go into action. Throughoutthe whole time of operation of the cooling device, the orifice 16 of thesteam pipe 15 which opens out into this zone, is in contact exclusivelywith steam, so that there is no possibility of the liquid phase enteringthe tube 15 and escaping to the exterior. If this were to happen, itwould seriously jeopardize the operation of the device and could evenrender it totally ineffective.

FIG. 3 is a theoretical graph outlining the operation of the devices inaccordance with the invention, whilst FIG. 4 shows experimental values.

The arrangement of the invention operates as follows:

With the operating voltage applied to the tube anode, the powerdissipated raises the temperature of the cooling fluid in the tanks,which temperature will be assumed to be initially 0,, (FIG. 3). When thetemperature reaches the value at which the vaporization pressure of thefluid is equivalent to the blowoff pressure of the valve 13, namely thepoint A on the graph of FIG. 3 (assuming that the valve bias pressurehas been set in an environment which is at atmospheric pressure P), thesaid valve opens and bleeds off steam. From this moment on, the whole ofthe power dissipated by the anode serves to vaporize the liquid, whosetemperature remains sta- .tionary at the level AB defined in FIG. 3. Thesystem continues to operate in this way until the liquid is exhausted,this corresponding to the point B in FIG. 3. Beyond the point B, i.e.assuming that the voltage is still applied to the anode after the fluidhas been exhausted, the anode temperature starts rising again asindicated by the section C of the characteristic. In the same FIG., A BC, is the curve which would be obtained with this same device, with thevalve calibrated in the same way for an external pressure P of around Imillibar. In this case, the valve would open at a vapor pressure lowerby about one bar than the pressure previously considered and therefore,at a temperature lower by AT than that corresponding to operation atatmospheric pressure.

FIG. 4 shows experimental values obtained on a prototype of the devicein accordance with the invention, using grams of water, the dissipatedanode power being 800 watts, the environmental pressure being normalatmospheric pressure (760 mm. Hg or 14.7 p.s.i.), the valve being set to2.7 bars (2.7 X 10 PA) absolute. The temperature plotted is that of thetube body at a point located between the tanks 2 and 3.

In this figure:

1 is the experimental curve of temperature versus time;

2. is the theoretical curve of temperature versus time (in the operatingconditions of the experiment);

3. is the curve of the absolute pressure in the tanks as a function oftime (Y-axis on the right of FIG. 4).

As the figure shows, the device may operate during a few minutes.

FIG. 5 illustrates a modification of the valve used in the device ofFIG. 1.

In this modified form. to allow for the possibility that the valve 13does not provide a perfect seal between the seating 13" and the valvemember l3'. a sealed cap 14 is soldered over the pipe 12 at 14'. using alow melting point solder (FIG. 5 The melting point of this solder isequal to the vaporization temperature as determined by the calibrationof the valve. or is lower than it by no more than about 30.

In operation. according to its melting temperature, the seal 14' meltseither when the valve 13 opens or some time before. and allows the vaporto escape.

By way ofexample one of the materials used to produce the seal 14 is theternary eutectic alloy Pb, Bi, Sn, known by the name of Darcct alloywhich melts at 96 C the proportions by weight being: Pb 0.32; Bi 0.155,and Sn 0.525.

The cooling arrangement of the invention is particularly useful in spaceresearch techniques, where the time of operation required is limited tothe time of operation of the missile in which they are mounted. Thiskind of application justifies the hypothesis of an external pressure ofl mb., which is the pressure prevailing at an altitude of some tens ofkilometers.

The same device could be operated continuously by replacing the plugsclosing off the orifices l and ll, by input and discharge pipingsystems, the water being circulated around the hot part of the tubethrough the groove 4, for example, from reservoir 3 to reservoir 2.

Of course. the invention is by no means limited to the embodimentdescribed and illustrated which has been given only by way of examplevlclaim:

l. A cooling arrangement for dissipating heat generated by an electrontube in motion with longitudinal and radial accelerations, out of reach.said arrangement comprising: a tight enclosure for a predeterminedamount of cooling liquid in thermal contact with said tube, saidenclosure comprising a valve opening out into the environment at oneofits two ends; means for adjusting the blowoff pressure of said valveas a function of the vaporization pressure of said liquid at apredetermined temperature. a pipe positioned within said enclosure andhaving an input and an output said output being tightly connected tosaid valve at the other end of said valve, said input being disposedsuch that, for any position of said arrangement during saidvaporization, said input is free from any contact with said liquid.

2. A cooling arrangement as claimed in claim 1, wherein said valve isobturated at said end opening out into the environment by a cap sealedwith a sealing material, the melting point of said sealing materialbeing below said predetermined temperature.

1. A cooling arrangement for dissipating heat generated by an electrontube in motion with longitudinal and radial accelerations, out of reach,said arrangement comprising: a tight enclosure for a predeterminedamount of cooling liquid in thermal contact with said tube, saidenclosure comprising a valve opening out into the environment at one ofits two ends; means for adjusting the blowoff pressure of said valve asa function of the vaporization pressure of said liquid at apredetermined temperature, a pipe positioned within said enclosure andhaving an input and an output, said output being tightly connected tosaid valve at the other end of said valve, said input being disposedsuch that, for any position of said arrangement during saidvaporization, said input is free from any contact with said liquid.
 2. Acooling arrangement as claimed in claim 1, wherein said valve isobturated at said end opening out into the environment by a cap sealedwith a sealing material, the melting point of said sealing materialbeing below said predetermined temperature.